Device for indicating the locking state of a fifth wheel coupling and sensor arrangement

ABSTRACT

A device is described for indicating the locking state of a fifth wheel coupling ( 1 ) and an arrangement of a first and a second sensor ( 6, 7 ).  
     According to the prior art, the first sensor ( 6 ) is arranged on the underside of the locking latch and monitors the position of the kingpin in relation to the locking latch ( 13 ). A second sensor ( 7 ) that is used is an inductive proximity switch that monitors a safety mechanism against loosening. In practice, this type of positioning of the first sensor ( 6 ) has led to damage of the locking latch ( 13 ) and the sensor ( 6 ), while the signals of the second sensor ( 7 ) were often false signals.  
     Thus, the object of the invention was to provide a device for indicating the locking state, which maximizes operational availability and minimizes false signals. A further object of the invention was to optimize the arrangement of the first and the second sensor ( 6, 7 ).  
     These objects were attained by arranging the first sensor ( 6 ) detecting the kingpin ( 3 ) in the area of the locating hole ( 2 ) and configuring the second sensor ( 7 ) as a magnetically sensitive sensor that interacts with a magnet ( 9 ) mounted on the operating lever ( 4 ). The two sensors ( 6, 7 ) are based on different mechanisms of action.

[0001] The invention relates to a device for indicating the lockingstate of a fifth wheel coupling, comprising an evaluation unit to whicha first and a second sensor are connected and a display unit which isconnected with the evaluation unit. The device further relates to anarrangement of a first and a second sensor on a fifth wheel with which akingpin in a locked state is engaged in a positive locking manner.

[0002] DE 198 20 139 A1 represents a generic prior art in thisconnection. This document describes a method and an arrangement formonitoring the proper locking and securing of a fifth wheel equippedwith a locking mechanism and a safety mechanism. A first sensor isprovided for monitoring the state of the locking mechanism and a secondsensor for directly or indirectly monitoring the state of the safetymechanism. The first sensor is an inductive proximity switch and isintended to be mounted on the underside of the locking latch and tomonitor the position of the kingpin in relation to the locking latch. Ifthe kingpin is driven in too high, it rises above the locking latch,which increases the risk of false detections. In practice, however, sucha positioning of the first sensor has proven to be a drawback becausethe locking latch must first be locked before the sensor can detect theposition of the king pin in relation to the locking latch. An incorrectpositioning of the kingpin led to increased wear and damage to thelocking latch and the first sensor mounted thereon, since the lockinglatch, even during travel, is subject to substantial impact loading,which is also transmitted to the first sensor. Another weak point is theflexibly installed cables. The second sensor is likewise an inductiveproximity switch, which monitors a locking mechanism that secures thesafety mechanism against loosening. For this purpose, a tongue of thelocking mechanism is monitored, which is within the detection range ofthe sensor only as long as the locking mechanism stays in a lockedposition in which the operating lever is secured by a cam. The essentialdrawback of the sensor arrangement of this second sensor is that thereare frequent false alarms because the major part of the fifth wheel ismade of steel, and actuating the operating lever changes the position ofa plurality of other components in relation to the second sensor, whichthen trigger a false signal.

[0003] Thus, the object of the invention is to provide a device forindicating the locked state that maximizes operational availability andminimizes false signals.

[0004] A further object is to optimize the arrangement of the first andthe second sensor.

[0005] These objects are attained by a device for indicating the lockingstate of a fifth wheel coupling, comprising a locating hole forreceiving a kingpin, an operating lever which in a locked position canbe fixed in a holding position, and an evaluation unit to which a firstand a second sensor are connected as well as a display unit connected tothe evaluation unit. According to the invention, the first sensor isarranged in the area of the locating hole and detects the kingpin, whilethe second sensor is a magnetically sensitive sensor, which interactswith a magnet mounted to the operating lever, such that the two sensorsare based on different mechanisms of action.

[0006] Basing the two sensors on different mechanisms of action, e.g. aproximity switch and a magnetically sensitive sensor, minimizes thepossible mutual influences as well as the risks of failure.

[0007] With respect to the coupling states that can be indicated on thedisplay unit, two states occur in normal operation. In a first state,the first sensor detects a kingpin and the second sensor confirms alocked position of the operating lever.

[0008] In a second state, the first sensor does not detect a kingpin andthe second sensor signals an open position of the operating lever, i.e.the tractor is currently driving without a semi-trailer with the fifthwheel ready for coupling.

[0009] If the operating lever is in its open position and the kingpin ispresent or the operating lever is in its closed position and the kingpinis not present, the display unit signals an error message to the driver.

[0010] Positioning the first sensor in the locating hole of the fifthwheel, preferably in an area opposite the locking latch, places thefirst sensor in an area that is subject to little wear. During thecoupling process, the tractor backs up against the stationarysemi-trailer, which for coupling with the fifth wheel of the tractor isprovided with a kingpin having an upper collar, a middle section with asmaller diameter for engaging with the locking latch of the fifth wheeland a lower collar. The first sensor can now sense, for example, thelower collar of the kingpin, which is already in the locating holewithout the locking latch being closed. If the kingpin is incorrectlypositioned, the driver can first make corrections while the fifth wheelis in its open position until the first sensor detects that the kingpinis horizontally and vertically in its correct position.

[0011] The second sensor used is a magnetically sensitive sensor.Suitable are, for example, reed sensors or Hall-effect sensors, whichinteract with a magnet located at a corresponding point of the operatinglever. The magnet preferably moves in the direction of the fixed secondsensor. Since no other magnets are normally present on the fifth wheel,false signals are minimized.

[0012] The display unit is preferably arranged in a driver's cab of atractor of a semi-trailer. Based on such an arrangement of the displayunit in the driver's cab, the driver receives information on theposition of the kingpin in relation to the fifth wheel or the positionof the operating lever in an area visible from the driver's seat. As aresult, the driver does not need to leave the cab during coupling anduncoupling to get this information. Furthermore, the position of theoperating lever is continuously displayed for the driver during traveland, in particular, after prolonged breaks.

[0013] The further object is attained, firstly, by a first sensormounted to a fifth wheel with which a kingpin in a locked state isengaged in a positive locking manner. A coupling plate for receiving theking pin has a complementary locating hole, and the kingpin has an uppercollar, a middle section with a reduced diameter for engaging with alocking latch and a lower collar. According to the invention, the firstsensor is disposed in the area of the locating hole below the couplingplate and detects the kingpin. The essential advantages are fixed cablesthat are not subject to continuous motion, reduced impact loading of thesensor and a reduced risk of false detections due to fixed installation.

[0014] Advantageously, the first sensor detects the lower collar of thekingpin. In the first place, the lower collar, unlike, for example, themiddle section with the reduced diameter, is subject to little wear, sothat the distance between the sensor and the lower collar remainsconstant even after a prolonged operating time. A further advantage ofdetecting the lower collar of the kingpin is that the first sensor canbe fixedly mounted in a protected area underneath the coupling plate ofthe fifth wheel.

[0015] Advantageously, the first sensor lies radially opposite of thelower collar of the engaged kingpin. Thus, an incorrect positioning orthe absence of the kingpin can be detected in all three spatialdirections.

[0016] Preferably, the first sensor is disposed in an area opposite thelocking latch. During normal travel, the kingpin contacts the lockinglatch with its middle section with the reduced diameter, such that wearoccurs in both components after a prolonged time, and they may have tobe replaced. The area of the locating hole opposite the locking latchcontacts the kingpin only when the tractor backs up and is thereforesubject to little wear. The locking latch can therefore be replaced inthe same manner as before, without the first sensor having to be removedand subsequently reinstalled and recalibrated in a time-consumingprocess. A further advantage is that the sensor can detect the kingpinwithout prior actuation of the locking latch. As a result, if thekingpin is incorrectly positioned, the fifth wheel coupling and, inparticular, the locking latch are not actuated and are consequentlyprotected from damage.

[0017] Advantageously, the first sensor can be a proximity switch.Proximity switches are defined as only inductively operating sensors.Such proximity switches are inexpensive, technically mature and caninteract with ordinary components made of steel, such that aconventional kingpin may be used.

[0018] The additional object is further attained by an arrangement of asecond sensor on a fifth wheel receiving a kingpin, on which a lockinglatch mounted underneath a coupling plate rotatably fixes the king pin.The locking latch can be brought into an open position or a lockedposition via a locking mechanism. This locking mechanism comprises anoperating lever, which in the locked position can be fixed in a holdingposition. The second sensor is mounted on the underside of the couplingplate to detect the holding position of the operating lever. Accordingto the invention, this second sensor is a magnetically sensitive sensorthat interacts with a magnet attached to the operating lever.

[0019] In contrast to the aforementioned proximity switches,magnetically sensitive sensors are defined as reed sensors orHall-effect sensors. Such sensors respond to the presence of a magneticfield and are therefore comparatively insensitive to adjacent steelcomponents that change their position.

[0020] In a special embodiment, the operating lever can comprise apivoted lever and a handle lever laterally displaceable thereon andsecuring the operating lever. The magnet is arranged on the handlelever.

[0021] Such an embodiment makes it possible to operate the fifthwheel—and consequently to switch between an open and closedposition—with one hand. In this case, the pivoted lever is securedmechanically in the same manner as before, e.g. with a notch-like recessthat engages with a wall or a cam of the fifth wheel. To be able toswing out the pivoted lever and thereby to release the notch-like recessfrom the wall, the handle lever must be laterally displaced relative tothe pivoted lever, such that a magnet disposed on the handle leverchanges its position in relation to the second sensor and therebyinfluences the magnetically sensitive sensor.

[0022] Preferably, the magnet is mounted on the coupling-side end of theoperating lever, particularly preferably on the coupling-side end of thehandle lever. This arrangement makes it possible to mount the secondsensor in a protected location within the fifth wheel. Mounting thesensor to the above-described embodiment of a one-handed actuation ofthe fifth wheel furthermore has the advantage that the second sensorsimultaneously detects the lever mechanism and thus also the pivotedlever, such that any defect in the area of the pivoted lever is alsodetected.

[0023] Advantageously, the second sensor is fixed in relation to thecoupling plate. As a result, the sensor itself, its connecting cablesand soldered connections are less subject to mechanical loading.

[0024] The invention will now be described in greater detail, by way ofexample, with reference to two drawing figures in which:

[0025]FIG. 1 is a longitudinal section of a fifth wheel with a kingpinand a first sensor, and

[0026]FIG. 2 is a bottom view of a fifth wheel with a first and a secondsensor.

[0027]FIG. 1 is a longitudinal section of the central area of a fifthwheel 1 with a kingpin 3 arranged in a locating hole 2 (cf. FIG. 2). Thekingpin 3 essentially has an upper collar 11, a middle section 12 with areduced diameter below that and a lower collar 14. For a positivelocking engagement of the kingpin 3 with the fifth wheel 1, a lockinglatch 13 pivotably supported on the coupling plate 10 engages with themiddle section 12 of the kingpin 3.

[0028] The first sensor 6 is disposed radially to the engaged kingpin 3in a reinforcing rib 21 where it is protected. It contactlessly detectsthe lower collar 14 of the kingpin 3 and sends an electrical signal viathe first sensor line 22 to the evaluation unit 5. In addition to thisfirst sensor line 22, a second sensor line 23 of the second sensor 7(see FIG. 2) is connected to the evaluation unit 5. A data line 24extends from the evaluation unit to e.g. the driver's cab of a tractor(neither of which is shown) where it is connected to a display unit 8.

[0029]FIG. 2 is a bottom view that shows the underside 17 of thecoupling plate 10 and a locking mechanism 16 engaging therewith. Thelocking lever 13 is in its locked position if a kingpin 3 is present.The first sensor 6 is accommodated in the reinforcing rib 21 on thelocating hole 2 in an area 15 opposite the locking latch 13.

[0030] The locking latch 13 is moved between an open position and thedepicted closed position via a locking mechanism 16. This motion istriggered via the operating lever 4, which protrudes from the fifthwheel 1, is constructed in two parts and can be actuated with one hand.Specifically, the operating lever 4 comprises the pivoted lever 18 andthe handle lever 19, which is mounted thereto so as to be laterallydisplaceable. In the depicted extended position of the handle lever 19,there is sufficient room in the lever opening 25 so that the pivotedlever 18 can likewise be laterally displaced and fixed by hooking theprojection 26 behind the cam 27. When the handle lever 19 is released,it is pulled in the direction of the coupling-side end 20 of theoperating lever 4 by the handle lever tension spring 28 and fills thelever opening 25 almost completely, so that the operating lever 4 isadditionally secured.

[0031] The above-described safety device is now monitored by a magnet 9arranged on the coupling-side end 20 of the handle lever 19, whichinteracts with a second sensor 7 mounted on the underside 17 of thecoupling plate 10. In case of a material fracture in components of theoperating lever 4 or the cam 27, the handle lever 19 could migrateoutwardly and the locking latch 13 could open as a result of vibrations.In this case, the distance between the magnet 9 and the second sensor 7would increase as the handle lever 19 migrates, which would be signaledto the driver via the display unit 8. List of Ref r nc Numerals 1 fifthwheel 2 locating hole 3 kingpin 4 operating lever 5 evaluation unit 6first sensor 7 second sensor 8 display unit 9 magnet 10 coupling plate11 upper collar 12 middle section 13 locking latch 14 lower collar 15area opposite the locking latch 16 locking mechanism 17 underside ofcoupling plate 18 pivoted lever 19 handle lever 20 coupling-side end 21reinforcing rib 22 first sensor line 23 second sensor line 24 data line25 lever opening 26 projection 27 cam 28 handle lever tension spring

1. Device for indicating the locking state of a fifth wheel coupling (1)comprising a locating hole (2) for receiving a kingpin (3), an operatinglever (4) which in a locked position can be fixed in a holding position,and an evaluation unit (5) to which a first and a second sensor (6, 7)are connected, as well as a display unit (8) connected with theevaluation unit (5), characterized in that the first sensor (6) isarranged in the area of the locating hole (2) and detects the kingpin(3), and the second sensor (7) is a magnetically sensitive sensor thatinteracts with a magnet (9) mounted to the operating lever (4), whereinthe two sensors (6, 7) are based on different mechanisms of action. 2.Device as claimed in claim 1, characterized in that the display unit (8)is arranged in a driver's cab of a tractor for a semi-trailer. 3.Arrangement of a first sensor (6) on a fifth wheel (1) with which akingpin (3) in a locked state can be engaged in a positive-lockingmanner, in which a coupling plate (10) has a complementary locating hole(2) to receive the kingpin (3), and the kingpin (3) has an upper collar(11), a middle section (12) with a reduced diameter for engaging with alocking latch (13) and a lower collar (14), characterized in that thefirst sensor (6) is arranged in the area of the locating hole (2) belowthe coupling plate (10) and detects the kingpin (3).
 4. Arrangement asclaimed in claim 3, characterized in that the first sensor (6) detectsthe lower collar (14) of the kingpin (3).
 5. Arrangement as claimed inclaim 3 or 4, characterized in that the first sensor (6) is radiallyopposite the lower collar (14) of the engaged kingpin (3). 6.Arrangement as claimed in any one of claims 3 to 5, characterized inthat the first sensor (6) is arranged in an area (15) opposite thelocking latch (13).
 7. Arrangement as claimed in any one of claims 3 to6, characterized in that the first sensor (6) is a proximity switch. 8.Arrangement of a second sensor (7) on a fifth wheel (1) receiving akingpin (3), in which a locking latch (13) arranged underneath acoupling plate (10) rotatably fixes the kingpin (3), the locking latch(13) can be brought into an open position or a closed position via alocking mechanism (16), the locking mechanism (16) comprises anoperating lever (4), which in the locked position can be fixed in aholding position, and the second sensor (7) is mounted on the underside(17) of the coupling plate (10) for detecting the holding position ofthe operating lever (4), characterized in that the second sensor (7) isa magnetically sensitive sensor, which interacts with a magnet (9)mounted on the operating lever (4).
 9. Arrangement as claimed in claim8, in which the operating lever (4) comprises a pivoted lever (18) and ahandle lever (19) laterally displaceable thereon and securing theoperating lever (4), characterized in that the magnet (9) is arranged onthe handle lever (19).
 10. Arrangement as claimed in claim 8 or 9,characterized in that the magnet (9) is mounted on the coupling-side end(20) of the operating lever (4).
 11. Arrangement as claimed in any oneof claims 8 to 10, characterized in that the second sensor (7) is fixedin relation to the coupling plate (10).